Setting bathtub in Mortar

[Kellymhall]

I am setting an American standard whirlpool in our bathroom that requires a mortar bed. I have watched very many YouTube videos on this. They all put tub in with dry floor to mark where stringer supports need to go. Then pull tub to pour mortar. My question is wouldn’t the mortar even squished down not allow tub rim to touch stringers. Or do you allow stringer height for mortar. So second question how high mortar and do stringers stay where they are or do you allow for height and how much do you allow. Thanks from stuck in mud!